Buggy code:
, new double [ ] { - 0.135352 , 0.478186 } , new double [ ] { - 0.061221 , 0.483371 } , new double [ ] { 0.003711 , 0.422737 } , new double [ ] { 0.065054 , 0.37583 } , new double [ ] { 0.108108 , 0.297099 } , new double [ ] { 0.123882 , 0.22285 } , new double [ ] { 0.117729 , 0.134382 } , new double [ ] { 0.085195 , 0.05682 } , new double [ ] { 0.0298 , - 0.019138 } , new double [ ] { - 0.02752 , - 0.072374 } , new double [ ] { - 0.102268 , - 0.091555 } , new double [ ] { - 0.200299 , - 0.106578 } , new double [ ] { - 0.292731 , - 0.091473 } , new double [ ] { - 0.356288 , - 0.051108 } , new double [ ] { - 0.420561 , 0.014926 } , new double [ ] { - 0.471036 , 0.074716 } , new double [ ] { - 0.488638 , 0.182508 } , new double [ ] { - 0.48599 , 0.254068 } , new double [ ] { - 0.463943 , 0.338438 } , new double [ ] { - 0.406453 , 0.404704 } , new double [ ] { - 0.334287 , 0.466119 } , new double [ ] { - 0.254244 , 0.503188 } , new double [ ] { - 0.161548 , 0.495769 } , new double [ ] { - 0.075733 , 0.49556 } , new double [ ] { 0.001375 , 0.434937 } , new double [ ] { 0.082787 , 0.385806 } , new double [ ] { 0.11549 , 0.323807 } , new double [ ] { 0.141089 , 0.22345 } , new double [ ] { 0.138693 , 0.131703 } , new double [ ] { 0.126415 , 0.049174 } , new double [ ] { 0.066518 , - 0.010217 } , new double [ ] { - 0.005184 , - 0.070647 } , new double [ ] { - 0.080985 , - 0.103635 } , new double [ ] { - 0.177377 , - 0.116887 } , new double [ ] { - 0.260628 , - 0.100258 } , new double [ ] { - 0.335756 , - 0.056251 } , new double [ ] { - 0.405195 , - 8.95E-4 } , new double [ ] { - 0.444937 , 0.085456 } , new double [ ] { - 0.484357 , 0.175597 } , new double [ ] { - 0.472453 , 0.248681 } , new double [ ] { - 0.43858 , 0.347463 } , new double [ ] { - 0.402304 , 0.422428 } , new double [ ] { - 0.326777 , 0.479438 } , new double [ ] { - 0.247797 , 0.505581 } , new double [ ] { - 0.152676 , 0.51938 } , new double [ ] { - 0.071754 , 0.516264 } , new double [ ] { 0.015942 , 0.472802 } , new double [ ] { 0.076608 , 0.419077 } , new double [ ] { 0.127673 , 0.330264 } , new double [ ] { 0.159951 , 0.26215 } , new double [ ] { 0.15353 , 0.172681 } , new double [ ] { 0.140653 , 0.089229 } , new double [ ] { 0.078666 , 0.024981 } , new double [ ] { 0.023807 , - 0.037022 } , new double [ ] { - 0.048837 , - 0.077056 } , new double [ ] { - 0.127729 , - 0.075338 } , new double [ ] { - 0.221271 , - 0.067526 } } ; public void doTestStRD ( final StatisticalReferenceDataset dataset , final LeastSquaresOptimizer optimizer , final double errParams , final double errParamsSd ) { } @ Test public void testKirby2 ( ) throws IOException { } @ Test public void testHahn1 ( ) throws IOException { } @ Test public void testPointCopy ( ) { AbstractLeastSquaresOptimizerAbstractTest . LinearProblem problem = new AbstractLeastSquaresOptimizerAbstractTest . LinearProblem ( new double [ ] [ ] { new double [ ] { 1 , 0 , 0 } , new double [ ] { - 1 , 1 , 0 } , new double [ ] { 0 , - 1 , 1 } } , new double [ ] { 1 , 1 , 1 } ) ; final boolean [ ] checked = new boolean [ ] { false } ; final LeastSquaresBuilder builder = problem . getBuilder ( ) . checker ( new org . apache . commons . math3 . optim . ConvergenceChecker < Evaluation > ( ) { public boolean converged ( int iteration , Evaluation previous , Evaluation current ) { Assert . assertThat ( previous . getPoint ( ) , not ( sameInstance ( current . getPoint ( ) ) ) ) ; Assert . assertArrayEquals ( new double [ 3 ] , previous . getPoint ( ) . toArray ( ) , 0 ) ; Assert . assertArrayEquals ( new double [ ] { 1 , 2 , 3 } , current . getPoint ( ) . toArray ( ) , AbstractLeastSquaresOptimizerAbstractTest . TOl ) ; checked [ 0 ] = true ; return true ; } } ) ; <START_BUG> Optimum optimum = optimizer . optimize ( builder . build ( ) ) ; <END_BUG> Assert . assertThat ( checked [ 0 ] , is ( true ) ) ; } class LinearProblem { private final RealMatrix factors ; private final double [ ] target ; public LinearProblem ( double [ ] [ ] factors , double [ ] target ) { } public double [ ] getTarget ( ) { } public MultivariateVectorFunction getModelFunction ( ) { } public MultivariateMatrixFunction getModelFunctionJacobian ( ) { } public LeastSquaresBuilder getBuilder ( ) { } } }

Fix:
optimizer . optimize ( builder . build ( ) ) ;